The ceramic heater 20 includes the ceramic substrate 22 and a hollow shaft 40. The ceramic substrate 22 is disk-shaped, and a resistance heating element 24 is embedded in the ceramic substrate 22. The hollow shaft 40 is attached to the center of a lower surface of the ceramic substrate 22. The ceramic substrate 22 has a rail groove 26 to which a slide lid 28 is attached and a guide groove 30 that serves as a thermocouple conduit. Moreover, a tube 32 is disposed outside the shaft 40. The tube 32 extends in the up-down direction and is connected to the guide groove 30.